I have a 1993 Ford F-150. It has failed emissions with the following numbers even after having installed a new thermostat, spark plugs, catalytic converter, distributor cap and rotor, new spark plug wires.

HC's are 432 on High speed test and 900 on low speed test
CO are 9.32 on high speed test and 8.74 on low speed test

Another curious thing is that I can't seem to get it up to operating temperature. It's operating around 120-130 but it has a new thermostat in it.

Any ideas

Thanks,

Russell

 

That's weird about the temp bieng low and it bieng new (t-stat) like that. My brother's 92 failed e-test bad, but when it was retested, it passed, say 10 minutes later. They tried this again, fail, then pass, fail and the truck left with a pass. Still didn't figure that one out. The engine was motorvaced out and all the usual was replaced, then she ran fine. Your #'s are pretty bad. Check the O2 sensors too. PCV valve as well.

 

Not getting up to operating temp could be huge part of the problem. Perhaps the new thermostat is stuck open.

Is this a motor with a carb or fuel injection? If a carb, the choke could be stuck open, or it does not close until you get to operating temp. If you have computer controlled injection, the low temps could be making the computer keep the choke on. The choke puts much more fuel into the motor.

 

I'm going to verify what temp it is operating at myself and then go from there.

Any tips on the best way to get an accurate reading.

Russell

 

DBD, the 300 was EFI in 87.

RLJ, how are you measuring your temp?

Adrianspeeder

 

Okay,

I just checked the engine temp and it is measuring 130.

I put a cheap temperature gauge into the open radiator and it never read above 130.

The upper radiator hose was cold and got warmer but it was never so hot that I couldn't leave my hand on it for a minute or two.

I'm sure the engine is operating above 130 but not by much.

It has a brand new thermostat in it so I can't imagine that this one is also failing. The heater, by the way works great, and the heater hoses are hot.
The a.c. on the other hand, is much warmer than it used to be. I'm not sure if the problems are related.

I really think the truck is failing emissions because the engine isn't heating up but I can't figure out why it's not. The car is not overheating so maybe it is stuck open, but how that could happen with a brand new one I do not know. This is the second thermostat I have played with in the last week.

Any IDEAS

Russell